Microtelephone



y 7, 1930. J. SCHNEIDER ET AL 1,760,566

MICROTELEPHONE Filed Feb. 2, 1929 Patented May 27, 1930 UNITED STATESPATENT; OFFICE JOHANN' SCHNEIDER AND GEORG- HECKMANN OF.FRANKFORT-ON-THE-MAIN, GER- MANY, ASSIGNORS TO THE FIRM FU'LD & 00.TIELEPHON' UI \TD TELEGRAPHEN-' WERKE A. Ga, FRANKFORT-ON-THE-MAIN,GERMANY MICROTELEPHONE Application filed February 2, 1929, Serial No.337,057, and in Germany February 3,1928.

The invention relates to micro-telephones,

particularly wherein the handle and the casing for the receiver and themicrophone are in one piece, being pressed or produced by 6 squirting.The purpose of the invention is a simplification of the outer and innerconstruction of such. micro-telephones, and consequently, a cheapeningof the manufacture and an improvement in the efliciency of the in-.strument.

Known micro-telephones have the disadvantage that the user can, at anytime, and Without any special appliances, obtain access to the sensitiveinternal parts of the microphone and of the receiver. It is true thatproposals are already known for preventing an unauthorized openlng ofthe mlcrophone or receiver casings, by making it only possible to openthese casings by means of special tools. These known micro-telephoneshave, however, the disadvantage that complicated and encumberingappliances must be fitted within the casings and that, further, for theoperation of the special appliances, openings must be provided in thecasings which are unnecessary for the proper purposes of the microphoneor of the receiver and which lead to a deterioration of the transmissionof speech.

By this present invention these disadvantages of known appliances areavoided. This is obtained in such a way that the walls of the casings(which are provided at their outer edge with internal threads) for thereceiver and microphone, (which'are formed in the known manner asself-contained units), protrude from the outer parts of the said unitsand that the cover parts of the casings are, by their side surfaces,perfectly screwed into the casings. In this connection the uter surfacesof the'cover parts are formed in such a manner that they do not offerany hold-to the hand. The openings provided in the cover parts for-theoscillations of the voice are, in this connection, formed in such amanner that a special tool can grip within them, so that an unauthorizedopenin of the casings by hand is impossible.

The invention is represented by way of ex- 50 ample in the drawing, thedescription of which will make it possible to recognize furthercharacteristic features of the invention.

The handle '1 is pressed or produced by squirting as a whole, togetherwith the casing 2 for the receiver unit 3 and the casing 4 for themicrophone unit 5, for example from usulating material. The walls 6 and7 reectively of the casings 2 and 4, are longer than the correspondingthickness of thereings in the casings for the tools, the openings 12 and13 of the cover parts are formed in a special manner. Thus, the opening12 of the cover part 10 for the receiver casing 2 is hexagonal so that acorresponding key can engage within the same and the speaking opening 13of the cover part 11 for the microphone casing 4 consists of slots,-intowhich corresponding projecting parts of a tool can be inserted.

The walls 6 and 7 of the casings are towards their outer ends, set offin shoulders or steps. Against these shoulders flanges or collars 26,14, respectively carried by the units 3 and 5 are applied, whilst thecover parts 10 and 11 are situated in front of the flanges or collars 26and 14. The units 3 and 5 are thereby maintained in a definite position.

Behind the microphone unit 5, and on a further shoulder of the Wall 7 ofthe microphone casing 4, a plate 15 is supported, which bears contactsprings 16 and 17 and terminals 18.

The contact springs 16 and 17 engage against the microphone unit 5 andconstitute the electrical connection with the two poles of themicrophone. The contact spring 16 is formed as a plate spring and bearsagainst a contact pin 19 at the-centre of the microphone unit- 5, Whilstspring 17 is formed with a ring 20,

which is pressed, When screwing-in the cover part 11, between the flangeor collar 14 of unit 5 and the corresponding shoulder of the wallof thecasing 7. With the terminals 18 of plate 15 are connected, on the onehand,

the wires of the flexible cord 21 and, on the other hand, the conductor22 leading to the receiver unit 3. These conductors 22 are conductedthrough a metallic tube 23 originally pressed into or formed by mouldingin the handle 1, which tube is itself used as a conducting connection.For this purpose tube 23 at its oints of entrance into the casings 2 and3 is provided with terminals 24 and 25, to which are fitted thecorresponding wire connections. With this arrangement it is onlynecessary to provide a very small recess in the cross section of handle,so that the handle retains a sufficient strength.

Having fully described our invention, what we desire to claim and secureby Letters Patent is 1. A micro-telephone comprising a handle carryingat opposite ends integral casings open at the front and interiorlyscrew-threaded, receiver and microphone units housed within therespective casings so that the walls of the casings project outwardsbeyond the said units, and covers having their edges screw-threaded andcompletely screwed into the open fronts of thecasings so as to engagethe interior threads thereof, said covers having their outer surfacesformed so that they cannot afford a grip for the hand.

2. A micro-telephonecomprising a handlecarryingatoppositeendsintegralcasings open at the front and interiorlyscrew-threaded, receiver and microphone units housed within therespective casings so that the walls of the casings project outwardsbeyond the said units, and covers having their edges screw-threaded andcompletely screwed into the open fronts of the casings so as to engagethe interior threads thereof, said covers aving their outer surfacesformed so that they cannot afford a grip for the hand, and havingnon-circular sound-oscillation apertures shaped so as to be adapted tobe engaged by the insertion of a tool.

3. A micro-telephone comprising a handle carrying at opposite endsintegral receiver and microphone casings open at the front andinteriorly screw-threaded at the outer ends and having interiorshoulders, receiver and microphone units housed within the respectivecasings and engaged with the interior shoulders so that the walls of thecasings project outwards beyond the said units, and covers havingtheirouter edges screw-threaded and completely screwed into the threadedopen fronts of the casings so as to retain the receiver and microphoneunits against their respective shoulders, said covers having their outersurfaces formed so that they cannot afford a grip for the hand. .7

4. A micro-telephone comprising a handle carrying,at opposite endsintegral receiver and microphone casings open at the front andinteriorly screw threaded at their outer ends,

a single interior shoulder on the receiver ;microphone units housedwithin the respective casings the receiver unit engaging the singleinterior shoulder of the receiver casing and the microphone unitengaging the outer shoulder of the microphone casing, so that the wallsof the casings project outwards beyond the said units, covers havingtheir outer edges screw-threaded and completely screwed into thethreaded open fronts of the casings so as to retain the receiver andmicrophone units against their respective shoulders said covers havingtheir outer surfaces formed so that they cannot afford a grip for thehand, and a plate supported against the inner shoulder of the microphonecasing.

5. A micro-telephone comprising a handle carrying at opposite endsintegral receiver and microphone casings open at the front andinteriorly screw-threaded at their outer ends, a single interiorshoulder on the receiver casing, two interior shoulders on themicrophone casing one near the inner end and the'other towards the outerend, receiver and microphone units housed Within the respective casingsthe receiver unit engaging the single interior shoulder of the receivercasing and the microphone unit engaging the outer shoulder of themicrophone casing, so that the walls of the casings project outwardsbeyond the said units, covers having their outer edges screw-threadedand completely screwed into the threaded open fronts of the casings soas to retain the receiver and microphone units against their respectiveshoulders said covers having they cannot afford a grip for the hand, anda plate supported against the inner shoulder of the microphone casing,said plate carrying contact springs engaging the poles of the microphoneunit and terminals for the connection of the conductors leading to themicrophone and receiver.

6.--A micro-telephone comprising a handle carrying at opposite endsintegral receiver and microphone casings open at the front andinteriorly screw-threaded at their outer ends, a single interiorshoulder on the receiver casing, two. interior shoulders on themicrophone casing one near the inner end and the other towards the outerend, receiver and microphone units housed within the respective casingsthe receiver unit engaging'the single interior shoulder of the receivercasing and the microphone unit engaging the outer shoulder of themicrophone casing, so

that the 'walls of the casings project outwards beyond the said units,covers having their outer edges screw-threaded and completely screwedinto the threaded open fronts of the casings so as to retaiii'the-receiver and mitheirouter surfaces formed so that crophone unitsagainst their respective shoulders said covers having their outersurfaces formed so that they cannot afford a grip for the hand, and aplate supported against the inner shoulder of the microphone casing,said plate carrying contact springs engaging the poles of the microphoneunit and termi nals for the connection of the conductors leading to themicrophone and receiver, the plate being held against its shoulder bythe contact springs pressing against the microphone unit.

7. A micro-telephone comprising a handle carrying at opposite endsintegral receiver and microphone casings open at the I front andinteriorly screw-threaded at their outer ends, a single interiorshoulder on the receiver casing, two interior shoulders on themicrophone casing one near the inner end and the other towards the outerend, receiver and microphone units housed within the respective casingsthe receiver unit engaging the single interior shoulder of the receivercasing and themicrophone unit engaging the outer shoulder of themicrophone casing, so that the walls of the casings project outwardsbeyond the said units, covers having their outer edges screw-threadedand completely screwed into the threaded open fronts of the casings soas to retain the receiver and microphone 3 units against theirrespective shoulders said covers having their outer surfaces formed sothat they-cannot afl'ord a grip'for the hand, a plate supported againstthe inner shoulder oi the microphone casing, and a metallic tube mouldedin the handle having terminals at opposite ends situated in the receiverand microphone casings respectively. a

In testimony whereoef we have aflixed our signatures. JOHANN SCHNEIDER.

GEORG HECKMANN.

